Filellum sp.

Castro Mendonça, Luana M., Parisotto Guimarães, Carmen R. & Haddad, Maria A., 2022, Taxonomy and diversity of hydroids (Cnidaria: Hydrozoa) of Sergipe, Northeast Brazil, Zoologia (e 21032) 39, pp. 1-65 : 28-29

Filellum sp.

Fig. 11E

Description: Colonies stolonal, up to 915 µm. Hydrothecae sessile, 315–915µm high, 68–123 µm wide, arising from the hydrorhiza at variable patterns. Hydrothecae with at least half of their size adnate to the substrate and the free part emerging in the opposite direction from the substrate at variable angles. Hydrothecal adnate portion tubular, with numerous external transverse grooves in the exposed portion. Free hydrothecal portion cylindrical, generally elongated, with margin uniform and smooth, generally with renovations.

Material examined: PCS – abundant infertile colonies from the dry and rainy season; VB – few infertile colonies from the dry season; SE – few infertile colonies from the dry and rainy seasons; JB – one infertile colony from the dry season.

Stations: PCS – 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16 e 17; VB – C1P56, C2P34, C3P56; SE – C1P34, C2P12, C2P34, C2P56; JB – C3P56.

Bottom: gravel, sand, and mud.

Taxonomic remarks: The specimens found in Sergipe resemble Filellum serratum (Clarke, 1879) . This species is known by several external transverse grooves in the adnate portion of hydrothecae. However, Marques et al. (2011) discussed that this character is not enough to distinguish it from F. antarcticum (Hartlaub, 1904) , F. magnificum Peña Cantero, Svoboda & Vervoort, 2004 and F. nitidum Watson, 2005 , because all of them has grooves in the adnate portion of hydrothecae. These authors also specified that only the coppina characteristics are sufficient to differentiate those species. As a coppinia was not found in material from Sergipe, a reliable identification was not possible.

Remarks: Colonies from PCS found on Porifera, Anthozoa ( Carijoa sp. ), Bryozoa, and an aglaopheniid hydroid, a bougainvilliid hydroid, Eudendrium carneum , a haleciid hydroid, Idiellana pristis , Obelia spp. , and Sertularelloides cylindritheca . Estuarine material was found on algae, Bryozoa, and the hydroids Cladocoryne floccosa , Corydendrium parasiticum , Eudendrium merulum , and Plumularia floridana .

Syntheciidae Marktanner-Turneretscher, 1890 Hincksella formosa (Fewkes, 1881) Fig. 14A–B

Synonyms available from: Galea (2013).

Sertularella formosa Fewkes, 1881: 130 .

Description: Colonies erect, up to 8 cm high, arising from a creeping hydrorhiza. Stem monosiphonic, divided into internodes by transverse and oblique nodes. Stem internodes giving rise to hydrothecae and hydrocladia, both disposed alternately. Hydrocladia 0.9–2.1 cm long, arising from the stem just below or behind the caulinar hydrothecae in angles of 83–96°. Stem separated into internodes by transverse nodes, each internode with a hydrotheca arising at the distal end, just below the node. Hydrothecae cylindrical, relatively short, 0.93–1.26 mm high, 0.53–0.77 mm of maximum width, arising from a long apophysis concerning the hydrothecal length, with a distinct septum separating the apophysis from the hydrothecae. Hydrothecae adcaulinar wall straight, abcaulinar one slightly convex in the medial portion. Margin smooth, with several renovations, aperture circular, without operculum. Gonothecae elongated, 1.9–2.4 mm high, 1.0– 1.4 mm wide, arising in a short pedicel at the lateral intersection between the stem and the hydrocladium. Adcaulinar and abcaulinar walls of gonothecae convex from the basal to the medial portion and concave in the distal portion. Gonothecal margin with three cusps and an operculum with four valves.

Material examined: PCS – few colonies, three of them with gonothecae, from the dry and rainy seasons. CZUFS CNI-00037; CNI-00142; CNI-00143.

Stations: PCS – 3, 11, 12, 15, 18.

Bottom: gravel, sand, and mud.

Distribution: Brazil – Bahia, sampled by the “Challenger Expedition (1873-1876)” ( Allman 1888, as Sertularia integritheca ). World distribution – widely distributed in tropical regions at Western and Eastern Atlantic ( Galea 2013).

Taxonomic remarks:The species was originally described as Sertularella formosa Fewkes, 1881 and, later as Sertularia integritheca Allman, 1888 . It was then relocated in the genus Synthecium (as S. formosum (Fewkes, 1881) , Migotto et al. 2002) and, later was changed to the genus Hincksella ( Grohmann et al. 2016) .

Remarks: unknown substrate.

Figures

Figure 11. (A-B) Calycella sp.: general view of a colony; (B) detail of a polyp; (C-D) Cirrholovenia tetranema: (C) general view of a colony highlighting a nematotheca (red arrow); (D) detail of a polyp with hydranth; (E) Filellum sp: general view of a colony.

Figure 14. (A-B) Hincksella formosa: (A) general view of a stem showing several hydrocladia with hydrothecae; (B) detail of the stem with a gonotheca (red arrow); (C-D) Hincksella pusilla: (C) general view of the distal part of a stem with hydrothecae; (D) detail of an intersegment with a hydrotheca; (E-G) Synthecium tubithecum: (E) general view of a stem showing stem and hydrothecae; (F) detail of a stem with a pair of hydrothecae bearing two male gonothecae; (G) detail of the stem with a pair of hydrothecae bearing two female gonothecae.